Essential oils of Citrus aurantifolia from Cameroon and their antifungal activity against Phaeoramularia angolensis

Essential oils of three varieties of Citrus aurantifolia (Bearss, Mexican and "Sans epines") grown in Cameroon were extracted by hydrodistillation with yields of 0.29, 0.57 and 0.25% respectively. The chemical analysis was carried out by gas chromatography and gas chromatography coupled with mass spectrometry. The three samples were found to be very rich in monoterpenes, and limonene was the major compound with 53.92, 43.53 and 51.98% respectively. The determination of the antifungal activity was done by the incorporation technique. The three extracts exerted an inhibiting action on the radial growth of Phaeoramularia angolensis which is fungicidal. The MIC obtained is 1.4 mg/ml for C. aurantifolia var. Mexican and 1.5 mg/ml for Bearss and "Sans epines" varieties. These three essential oils could constitute an alternative to chemical fungicides usually used for Citrus fruit crops. In addition, the essential oil of the Bears variety was fractionated and the fractions were tested in order to determine the active compounds. The most active fractions are rich in neral and geranial, compounds which could thus be responsible for the activity of the crude extract.